I'm not sure if things are different for a trust (and whether the ATF would scrutinize it more), but a company can incorporate in any state it chooses. The company may have to file another form for a 'foreign entity' because it's out of state, but it isn't that big of deal. Most companies will incorporate in Delaware or Nevada due to different tax and employee laws. I don't see why a person trying to incorporate should be any different.

i've heard of guys living in Missouri, and owning suppressors that reside in safety deposit boxes in the state of Kansas since they passed their suppressor law before ours. When ours goes into effect in august or sept, they'll bring them across the state lines.